Calculating output impedance in linear networks without source nulling or load disconnect: the instantaneous output impedance

Summary This paper derives exact expressions for the output impedance of a voltage‐excited (current‐excited) linear network without having to nullify (kill) the exciting source or disconnect the load. The derived expressions show that the instantaneous output impedance is both source and load dependent, but when the source is nullified, the output impedance becomes independent of the load, as expected. For some special networks, the output impedance is also independent of the load. The expressions are verified for a number of known circuit setups and experimentally on a gyrator‐based linear network, which has an output impedance that can switch between positive and negative values. Copyright © 2015 John Wiley & Sons, Ltd.